Also in custody is another Canadian, Jesse Jude Mara, 21. Police refused to say where in Canada he's from.

A third woman and her two children, including an 11-year-old girl, are being held with several dozen members of the cult in various child welfare institutions across this South American city.

They were detained last week following a series of raids on nearly a dozen Buenos Aires homes. Police placed 17 adults - including the two Canadians - in custody. They will be questioned, starting today, by Federal Judge Roberto Marquevich.

Twelve of the 17 have been formally accused of conspiracy to kidnap and conceal children. The judge will determine whether formal charges will be laid after he completes his questioning.

Marquevich ordered the raids after former cult members reported alleged incidents of kidnapping, physical and sexual abuse of children, incest and prostitution.

"This is not the kind of thing that my sister would be directly involved with," Steve Borowick said last night.

"I know my sister. From a moral standpoint, anybody who knows her would find it exceedingly difficult to believe that she would be involved in anything like what is being alleged."

Borowick, of Burlington, said his sister become the spokesperson for the group because she has been living with them since 1981, and as such has become the target of the investigation now under way.

He said his mother and various other family members have visited the group on several occasions.

"They have never seen, absolutely never seen any of the things that are being written about," Borowick said.

He said his sister travelled to South America when she was 13 years old as a member of a group sponsored by the local Rotary Club and spent a year in Argentina.

She finished high school in Burlington and then returned to live in Argentina.

She married a man, who is also a member of the group, but has since separated from him.

Susan Borowick has a 12-year-old son. Her brother believes he is now with the more than 140 children taken to state institutions since the raids. Reports indicated they were undergoing medical tests to determine whether they had suffered any physical or sexual abuse.

Marquevich has spent most of the weekend examining videos, books and magazines seized during the raid. One of the tapes seized shows a father having sex with his daughter; another shows children masturbating in front of adults.

Marquevich yesterday told an Argentine television station that prosecutors would try to prove the existence of a prostitution network led by the cult leaders.

However, the cult's lawyer, Hafez Zeine, said the family had been previously targeted on similar charges but that judicial authorities have never been able to prove anything. He described the group as a "missionary community," whose members don't smoke, or drink alcoholic beverages and dedicate their lives to God.

Steve Borowick said he hasn't been in touch with his sister for at least six weeks, but at that time she told him she was involved with trying to refute the allegations brought against the group by former cult members.

He said it is his understanding that the charges were laid by two former group members who broke away from the sect.

"I don't know whether these people witnessed something or whether it's sour grapes on their part," Borowick said. "It is my understanding that when somebody has been with a sect for a long period of time and then leaves the group, that extreme bitterness exists afterwards."

He described the group as being not unlike many other small religious groups that exist throughout North America.

"They struggled to raise money to live," he said. "All of the children are . . . taught by members of the group and all of the children probably have a higher level of education than the surrounding population."

The group is well known in Argentina and the children have sung on national television and radio, he said.

Susan Borowick, a long-time member of the sect was also arrested following a 1989 police sweep of cult residences, according to Canadian embassy officials here.

She was released after spending a month in custody when Argentine justice officials decided not to proceed with charges against her; Mara, also arrested at the time, was also released without charges.

Authorities say they are having enormous difficulties identifying children by their family names because of the cult's poor record- keeping.